Fig. 1. Multiple scattering of laser in water

Fig. 2. Schematic diagram of double collision scattering coordinate system of a single photon

Fig. 3. Program diagram of photon simulated motion

Fig. 4. Simulation of pure water backscattering echo light signal with different attenuation coefficients

Fig. 5. Variation of peak photon number of pure water backscattering with different attenuation coefficients

Fig. 6. Backscattering simulation of pure water with different scattering rates

Fig. 7. Experimental system diagram

Fig. 8. Echo diagram of backscattered signal of water body. (a) Diagram of complete echo signal; (b) Diagram of forward time echo signal

Fig. 9. Variation diagram of peak signal amplitude with turbid

Fig. 10. Diagram of pulse width with turbidity